#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
#define rep(i, a, b) for (int i = (a); i <= (b); i++)
#define per(i, a, b) for (int i = (a); i >= (b); i--)
#define endl '\n'
const int N = 2e5 + 5;

int n, k, m;
int a[N], sum[N], ans = 2e5;

int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  cin >> n >> k >> m;
  rep(i, 1, m) {
    int x;
    cin >> x;
    a[x] = 1;
  }
  rep(i, 1, n) {
    sum[i] = sum[i - 1] + a[i];
    if (i >= k) ans = min(ans, sum[i] - sum[i - k]);
  }
  cout << ans;
  return 0;
}